One of the main tasks for biological research today is to decipher a whole system of biologically relevant information that exists on the cell surface. It has recently come to be appreciated that the regulation of the number and distribution of membrane components is one way in which this information is expressed. But the basic biochemical mechanisms underlying these regulatory mechanisms are largely unknown. Two cell surface macromolecules whose number and distribution are highly regulated both in vivo and in vitro are the acetylcholine receptor (ACHR) and the acetylcholinesterase (ACHE). These macromolecules are particularly interesting to focus on. 1) They have been fairly extensively studied and hence good tools have already been developed for their study. 2) They are essential components of the neuromuscular junction and their study promises a greater understanding of both the cell surface and cholinergic synapses. 3) These molecules are also useful for the study of various muscle pathologies such as the muscular dystrophies. We have recently shown that the route of intracellular transport of the ACHR and ACHE are distinct. We have shown this with the aid of the monovalent ionophores which we and others have shown inhibit the intracellular transport of secretory glycoproteins. We will now see the monovalent ionophores to decipher the mechanism by which secretory and integral membrane glycoproteins are transported through the cell and the routes that are utilized.